The U.S. Environmental Protection Agency (USEPA) recently released Phase II of its National Stormwater Calculator and Climate Assessment Tool package. The calculator is a desktop application that estimates the annual amount of stormwater runoff from a specific location. The app now includes changes in seasonal precipitation levels, the effects of more frequent high-intensity storms, and changes in evaporation rates based on validated Intergovernmental Panel on Climate Change scenarios.

The updated calculator also includes climate models that can be incorporated into the calculation of stormwater runoff. This adds future climate scenarios to the prior year's Phase I release, which included local soil conditions, slope, land cover, and historical rainfall records. Users can enter any U.S. location and select different scenarios to learn how specific green infrastructure changes, including inexpensive changes such as rain barrels and rain gardens, can reduce stormwater runoff. This information shows users how adding green infrastructure, which mimics natural processes, can be one of the most cost-effective ways to reduce stormwater runoff.

Click here to access more information about the USEPA's stormwater calculator and to download the app.